on the top of the stem. Each fraction has a distinct surface structure
(Hoshikawa, 1989) and chemical composition (Jin and Chen, 2006).
To evaluate the effect of morphological part, whole rice straw
was manually divided up into four parts; leaf blade, leaf sheath,
stem, and panicle. Whole rice straw and these three morphological
parts except for the panicle were grained in aWiley mill (WT-150;
Miki seisakusho, Japan) until they passed through 1-mm screen
to make whole powder, leaf blade powder, leaf sheath powder
and stem powder. These raw materials were stored in an air-dried
state.
Binderless boards were manufactured by one-step hot-pressing.
Table 1 shows the manufacturing conditions for the five types of
raw materials. The boards were 300mm×300mm×5mm, and the
target density was 0.8 g/cm3. The manufacturing method was based
on the study of Okuda and Sato (2004). All materials were handformed
into homogeneous single-layered mats in a forming box.
After forming, the mats were manually pre-pressed, and their top
and bottom surfaces were covered with aluminum foil. The mats
were then pressed with a hot-press machine under the condition
shown in Table 1. Two boards were manufactured for each raw
material.